Steering columns for motor vehicles are often designed for adjustable positioning of the steering wheel for improved driver comfort. Commonly, such steering columns can be provided with an adjustable rake, which allows angular adjustment of the steering wheel in up and down directions. Also, the steering column may be provided with a telescoping, or telescope adjustment which allows the steering wheel to be moved closer to or farther away from the driver.
To accomplish the rake and telescope adjustments, the steering column is typically provided with a compression bracket which is moveably carried in a stationary capsule bracket which is fixed relative to the vehicle. Thus, when the steering column is adjusted for rake, the compression bracket moves angularly up and down relative to the stationary capsule bracket. However, when the steering wheel is adjusted for reach, i.e. telescoping movement, the compression bracket typically remains stationary along with the capsule bracket while other components of the steering column assembly accomplish the telescoping movement. A locking mechanism is provided between the capsule and compression brackets to selectively lock them together in an adjusted position. When the locking mechanism is in an unlocked condition, the rake and telescope of the steering column can be adjusted. An operator selectively actuates either a manual, pneumatic, hydraulic or electromotive system to cycle the locking mechanism between the locked and unlocked conditions.
In the case of locking mechanisms which are actuated by electromotive devices, such as an electric motor, it has been the case that the motor must be located proximate to the locking mechanism and capable of reversing directions so that the locking mechanism can be cycled between its locked and unlocked conditions. However, these two aspects present certain design difficulties. For instance, locating the electric motor near the locking mechanism usually results in reduced design flexibility to the engineer. Providing a motor which can reverse directions has frequently resulted in the use of linear motors which, in solenoid type fashion, stroke back and forth when energized.
There exists a need for an improved locking mechanism for an adjustable steering column assembly which overcomes the disadvantages and design restrictions characteristic of the prior art.